Refractive or reflective optical sights are used in a wide variety of applications to obtain increased magnification of a scene. In one common application, an optical sight is affixed to the upper side of the barrel of a rifle-type weapon used by a soldier or a hunter. The user sights through the optical sight to acquire a target and aim the weapon toward the target to increase the likelihood of hitting the target with a projectile fired from the weapon.
A reticle is typically provided in the optical path of the optical sight to aid the user of the weapon in aiming the weapon. The reticle normally has reference markings or other information that aids the user in aiming the optical sight and thence the weapon toward the intended target. The reference markings usually include a cross hair, bulls-eye, center dot, or similar marking to indicate the bore sight of the weapon. The reference markings may also include elevation, windage, and other reference markings that assist the user in aiming the weapon.
In some designs, the reticle is illuminated by an artificial light source within the optical sight. The user of reticle illumination adds cost and weight, but it ensures that the reticle will be visible in a wide range of lighting conditions including normal daylight, low-light ambient conditions, and, particularly for infrared and other optical sights to be used at night, near-darkness conditions. If the reticle is not visible to the user, its advantages are lost.
There is a need for an approach to ensure proper illumination of the reticle of an optical sight, so that the reticle always remains visible to the user peering through the optical sight. The present invention fulfills this need, and further provides related advantages.